This relates generally to displays, and, more particularly, to backlit displays.
Electronic devices often include displays. For example, computers and cellular telephones are sometimes provided with backlit liquid crystal displays. Edge-lit backlight units have light-emitting diodes that emit light into an edge surface of a light guide plate. The light guide plate then distributes the emitted light laterally across the display to serve as backlight illumination. Direct-lit backlight units have arrays of light-emitting diodes that emit light vertically through the display.
Direct-lit backlights may have locally dimmable light-emitting diodes that allow dynamic range to be enhanced. If care is not taken, however, the light produced by a direct-lit backlight may not be sufficiently uniform. For example, variations in the distance between the light-emitting diodes and an overlapping diffuser layer may lead to undesired uniformity variations in a backlight.